could not receive mails from dovecot pop3

Hi Greetings. I have windows server2012R2  and installed Hypervisor  I have installed Ubuntu 16.04 server edition in Virtual machine(hyper-v 2012r2)  Postfix and dovecot are running  dovecot version :2.2.22 (fe789dz)  Able to send mail is ok. mail received in /var/mail/%u  could not receive mail from client Thunderbird.  the only changed option is disable_plaintext_auth = no  Never touched any other option. Ubuntu server ip : 192.168.1.250  (firewall in inactive)client ip : 192.168.1.1 (thunderbird is running in widows server (ip:192.168.1.1)let know how to save the output of dovecot -n from Ubuntu server machineThunder bird settings are: Thankyou.Baskaranand